On 02/03/2016 10:44 AM, Ingo Molnar wrote:
> Yuck, I don't really like this.
>
> Lockdep initialization must happen early on, and it should happen in a well
> defined place, not be opportunistic (and relatively random) like this, making
> it
> dependent on config options and calling contexts.
>
> Also, in addition to properly ordering UBSAN initialization, how about fixing
> the
> silent crash by adding a lockdep warning to that place instead of an
> auto-init?
>
> The warning will turn lockdep off safely and will generate an actionable
> kernel
> message and stackdump upon which the init ordering fix can be done.
>
Something like this already done for DEBUG_LOCKDEP=y (except it initializes
lockdep instead of turning it off).
look_up_lock_class():
...
#ifdef CONFIG_DEBUG_LOCKDEP
/*
* If the architecture calls into lockdep before initializing
* the hashes then we'll warn about it later. (we cannot printk
* right now)
*/
if (unlikely(!lockdep_initialized)) {
lockdep_init();
lockdep_init_error = 1;
lock_init_error = lock->name;
save_stack_trace(&lockdep_init_trace);
}
#endif
Silent crash happens only in DEBUG_LOCKDEP=n && LOCKDEP=y combination.
So, what about simply removing this #ifdef (and the other one in lockdep_info()
)?
I
